S3_PING doesn't work with S3 buckets created in Frankfurt region

I tried to use S3_PING with access and secret key pair. However, I got 400 (Bad Request) error. After some investigation, I found that modern S3 buckets created in Frankfurt needs amazon v4 authentication, which needs hmac-sha256. But now S3_PING supports only hmac-sha1, so I see no way to use S3_PING with buckets in Frankfurt region.